The reflector of a microwave reflector antenna is adapted to concentrate a reflected beam from a distant source such as a satellite upon a feed assembly positioned proximate a focal area of the reflector. In satellite communications systems such as consumer broadcast satellite television and or internet communications, a single reflector antenna having multiple feeds may receive signal(s) from multiple satellites arrayed in equatorial orbit. A central feed is arranged on a beam path from a center satellite to the reflector and from the reflector to the feed. Subsequent feeds for additional satellite beam paths use the same reflector but are arranged at an angle to either side of the central feed beam path. Alternatively, two feeds may be equally offset from the center position.
To minimize interference between closely spaced beams, adjacent satellites may be configured to use different operating frequency bands, such as the Ka and Ku frequency bands. Therefore, each antenna feed assembly is optimized for the corresponding frequency band. Each feed typically incorporates a low noise amplifier (LNA) circuit positioned proximate the feed input to amplify initially weak received signals before further degradation and or signal loss occurs. Signals from the multiple feed outputs may be mixed to a lower intermediate frequency and combined together via diplexer and switch circuitry proximate the feeds to allow multiple feed signals to be combined for transmission to downstream equipment on a common transmission line.
Multiple satellite spacing for consumer satellite communications systems previously required a larger degree angle of beam separation which could be implemented by arraying multiple individual beam path feed assemblies spaced away from each other, for example at a distance of 60 mm. Increasing demand for additional consumer satellite capacity/content has created a need for reception capability of satellites spaced closer together in orbit, for example requiring beams with a 1.8 degree angle of separation. For a similar sized reflector, this beam spacing requires a smaller 18 mm feed spacing. Prior cost effective individual feed assemblies are typically too large to allow an adjacent feed assembly spacing of 18 mm. Larger reflectors may be applied to increase the required feed spacing but an increased reflector size is commercially undesirable.
Prior high density multiple feed RF assemblies have used separate feed waveguide castings to increase the physical separation between the LNA inputs. Alternatively, if the feed spacing is sufficiently large, the waveguide to microstrip launch for each feed is contained on a single PCB. In this case, a separate waveguide “manifold” casting may be applied. The additional components and associated waveguide junctions add cost, manufacturing variables and or introduce potential failure points to the resulting assembly.
The increasing competition for mass market consumer reflector antennas has focused attention on cost reductions resulting from increased materials, manufacturing and service efficiencies. Further, reductions in required assembly operations and the total number of discrete parts are desired.
Therefore, it is an object of the invention to provide an apparatus that overcomes deficiencies in the prior art.